Abstract

When disability-adjusted life years are used to measure the burden of disease on a
population in a time interval, they can be calculated in several different ways: from
an incidence, pure prevalence, or hybrid perspective. I show that these calculation
methods are not equivalent and discuss some of the formal difficulties each method
faces. I show that if we don’t discount the value of future health, there is a sense
in which the choice of calculation method is a mere question of accounting. Such questions
can be important, but they don’t raise deep theoretical concerns. If we do discount,
however, choice of calculation method can change the relative burden attributed to
different conditions over time. I conclude by recommending that studies involving
disability-adjusted life years be explicit in noting what calculation method is being
employed and in explaining why that calculation method has been chosen.